1. Claim of Priority
The present application claims priority to Taiwanese Patent Application No. 098122480 filed on Jul. 2, 2009 and Taiwanese Patent Application No. 099121792 filed on Jul. 2, 2010.
2. Field of the Invention
The present invention relates to an organic light emitting diode (OLED) display, and more particularly, to an organic light emitting diode touch display.
3. Description of the Related Art
With a rapid development of monitor types, novel and colorful monitors with high resolution, e.g., organic light emitting diode (OLED) displays, are indispensable components used in various electronic products such as monitors for notebook computers, personal digital assistants (PDAs), digital cameras, and projectors. The demand for the novelty and colorful monitors has increased tremendously.
Luminous intensity of organic light emitting diode displays is determined by forward bias current of a light emitting diode (LED), differing from traditional liquid crystal displays (LCDs) on the market employing the voltage applied on liquid crystal pixels to determine pixel luminance. Deploying a self-illuminating technology, OLED displays do not require backlight, and further they can provide faster response time than LCDs do. Besides, OLED displays still have advantages, such as a better contrast ratio and a broader visual angle.
In order to facilitate carrying and utilizing OLED displays, OLED touch display panels that users can touch directly have become one of the tendencies of market development. Traditionally, OLED resistance or capacity touch panels, upon which additional resistance or capacity devices are placed, judge position coordinates of touch points by detecting voltage variations in the touch points. However, components, such as resistance devices and capacity devices, are placed on a panel directly, so it results in a decrease in light transmittance of OLED panels and an increase in total thickness of the panel. As for optical touch panels, they are OLED panels that are encircled with a large quantity of light sources and corresponding optical sensing devices, which are utilized to detect light of the corresponding light sources to judge position coordinates of touch points. Optical touch panels are divided into two sensing types: optical shadow type and optical reflective type.
The optical shadow type indicates that, under operational conditions of abundant ambient light, an optical touch panel is judged whether or not to be touched depending upon variations in ambient light. For example, when an object (e.g., a finger, a touch pad pencil, etc.) touches a pixel in one bright space, the light sensor of the touched pixel senses lower environmental brightness than that of the untouched pixels does. An OLED display system concludes that a pixel sensing lower light brightness is touched and other pixels with higher light brightness is untouched.
The optical reflective type indicates that, under operational conditions of dim environment, an optical touch panel is detected whether or not to be touched depending upon variations in reflected light of an OLED backlight. For example, in one gloomy space where backlight brightness is higher than environmental brightness at this time, when an object (e.g., a finger, a touch pad pencil, etc.) touches a pixel, the light sensor of the touched pixel senses higher light brightness than that of the untouched pixels does, for light from the backlight is reflected to the light sensor of the touched pixel via the object. An OLED display system concludes that a pixel sensing higher light brightness is touched and other pixels with lower light brightness is untouched.
However, light produced by the backlight is quite weak after being reflected, so under conditions of dim environment the signals that are sensed by the light sensor are usually weak, and signal recognition is less accurate as well. Moreover, if images, surrounding the zone that needs touching being at lower gray level (e.g., black), are intended to be dragged, it is easier to result in being unable to sense because of lack of light quantity of pixels.